Asphalt-base mastic



Unittid States Patent ASPHALT-BASE MASTIC Joe William Stewart, Milwaukee, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York No Drawing. Application April 2, 1956 Serial No. 575,320

7 Claims. (Cl. 106269) This invention relates to a mastic composition and more particularly to an asphalt-base mastic for sealing joints between two or more glass or enamel coated articles.

An object of the present invention is to provide a sealing mastic which, when applied to a. surface, will not appreciably shrink or pull away from the surface on curing or aging.

Another object of the invention is to provide an asphalt-base mastic having excellent cohesion between particles and excellent adhesion to both wet and dry glass or enamel articles.

Still another object is to provide a sealing mastic which will skin over to provide a tack-free outer surface in a very short period of time.

A further object is to provide an asphalt-base mastic which is resistant to the corrosive effect of silage juices or the like.

Another object is to provide a mastic which will not flow at room temperatures under atmospheric pressures.

Another object is to provide an asphalt-base sealing mastic in which the solvent when boiling out of the compound will not disturb the seal.

Another object is to provide a sealing mastic which may be pumped and applied toa surface by extruding through a nozzle.

The present invention is directed to an asphalt-base sealing mastic having greatly improved physical properties due to the presence therein of the combination of a metal fatty-acid non-gelling soap and an ammonium salt.

A typical asphalt-base sealing mastic embodying the present invention has the following general composition:

Percent Asphalt 40-60 Solvent ll-23 Filler material 20-40 Metal fatty-acid soap 1-3 Ammonium salt 2-6 Plasticizer 2-6 Anti-oxidant 0.1-1

dissolve the asphalt and has a relatively high boiling temperature of over 150 F. The solvent may include such compounds as carbon disulfide, carbon tetrachloride, or an aromatic hydrocarbon such as xylene, benzene, toluene, etc. Xylene in particular is a very desirable solvent for it has a sharp boiling point and thus is easier to use in cutting back the asphalt. In addition, ,the

ice

xylene is less toxic than some of the other aromatic hydrocarbons. By using a relatively high boiling point solvent, such as xylene, the solvent will not boil out and cause pot holes in the composition at temperatures below F.

The filler material is preferably a fibrous absorbent material such as asbestos, ceramic, glass or synthetic fibers or any other fibrous material which will not dissolve in water or in the solvent. The fibrous filler serves as a cushioning agent when the articles to which the sealing compound is applied are mechanically secured together and prevents the articles from being forced into actual contact by the attachment. This cushioning action permits the sealing compound to be retained between the adjacent surfaces of the articles rather than being squeezed therefrom by pressure of the mechanical attachment.

The fibrous filler material should preferably have absorbent qualities so that the individual fibers embedded in the sealing compound will serve as a wick and aid in the evaporation of the solvent. This property enables the solvent to pass through the fibers by a wick action toward the outer surface of the compound where the solvent may be exposed to the atmosphere and readily evaporated.

In addition to the fibrous filler material, any of the common'granular filler materials, such as calcium carbonate or whiting clay, may be added to the sealing compound to give the same the necessary Weight and body. It has been found that a filler consisting of about 50% fibrous material and 50% granular material is very satisfactory for many operations. However, the proportions of the fibrous and granular components may be widely varied depending on the particularconditions of operation and the asphalt and solvent employed.

The metal fatty-acid soap isemployed as a wetting agent to control the surface tension and wetting characteristics of the sealing compound so that the compound will readily coat the surface of the articles and promote adherence between the article and the sealing compound. The metal fatty-acid soap may be the salt of any one or more of the higher fatty acids having about 8 to 20 carbon atoms, such as stearic acid, lauric acid, oleic acid, palmitic acid and the like, and a metal, such as sodium, potassium, aluminum, calcium, zinc and the like.

The ammonium salt in combination with the nongelling soap decreases the tack free time of the sealing compound and aids in providing the compound with a tough outer skin in a very short period of time. In addition, the soap and the ammonium salt are thought to combine to give the compound excellent adherence and enable the same to be applied to wet and dry surfaces with equal success. The ammonium salt is preferably employed in a 2 to 1 ratio to the metal fatty-acid soap. That is, for every weight unit of soap employed, two weight units of the ammonium salt should be employed to obtain the most satisfactory qualities in the mastic.

It has been found that the ammonium ion (NHfl) is desired in the present composition and thus both inorganic and organic ammonium salts can be employed and also ammonium salts that are water soluble and those that are relatively insoluble in water. Examples of ammonium salts that have been used are ammonium oxalate, ammonium chloride, ammonium chlorate, ammonium permanganate, ammonium silico fluoride, ammonium bicarbonate, ammonium sulfate, and ammonium sulfide.

The plasticizer may consist of a non-drying oil such as polybutene and may be added to the compound, depending on the plastic qualities of the particular asphalt employed, to keep the compound pliable and prevent hardening with age. If a non-drying oil is used, it is desirable to also employ a small amount of an antioxidant material, such as Ag erite resin, to prevent the oil from oxidizing, as oxidiation over a period of time is apt to produce cracks in the sealing compound.

A preferred analysis of the sealing compound is as follows:

Percent Asphalt 49.9 Solvent 15.0 Fibrous filler material 14.3 Granular filler material 13.2 Ammonium salt 3.0 Metal fatty-acid soap 1.5 Plasticizer 3.0 Anti-oxidant 0.1

A specific illustration of the mastic is as follows:

Percent Asphalt (melt point 175 F. needle penetration of 17/10 mm. at 77 F.) 49.9 Xylene 15.0 Asbestos fiber 14.3 Calcium carbonate 13.2 Ammonium chloride 3.0 Aluminum stearate 1.5 Polybutene 3.0 Anti-oxidant 0.1

The proportions of the ingredients of the sealing mastic may be varied slightly in accordance with the temperature conditions prevailing at the time of application to provide greater fluidity for colder weather and lesser fluidity for warmer weather. The fluidity of the compound may be readily varied by altering the relative amounts of asphalt and solvent. For example, the above preferred composition is particularly adapted to be pumped and applied to a surface at temperatures over 60 F. If the mastic is to be pumped and applied at lower temperatures, down to 35 F., the proportions of asphalt and solvent may accordingly be' varied to about 46.5% and 18.5% respectively. tion of the plasticizer, if employed, may also be varied to conform to temperature conditions. At working temperatures of over 60 F. about 3% plasticizer is preferred, while at working temperatures below 60 F. and down to 35 F., about 4.8% plastcizer is desirable.

An illustration of a composition of the sealing mastic which is capable of being pumped at temperatures down of 35 F. is as follows:

To prepare the sealing mastic the asphalt is heated to the molten state which generally requires a temperature in the range of 375-400 F. The asphalt is then pumped into the mixing vessel and the solvent is added while agitating the asphalt to form a thick solution. As solvent is evaporated during this mixing operation and also during the subsequent operations, a predetermined excess of solvent is usually added to the mixing vessel.

After the asphalt is in solution, the mixture is cooled to a temperature of about 90 -100 F. and the filler,

In addition, the proporerties of the mastic.

ammonium chloride and soap are added to the mixture in the proper amounts. The soap will go into solution While the ammonium chloride will remain in suspension.

A solvent content test is then run on the mixture and the necessary additions of solvent, if any, are made to obtain the proper concentrationof solvent.

The non-drying oil and anti-oxidant are then added, if desired, and the resulting mixture is agitated for about 15 minutes.

If desired, the mixture may then be homogenized to give the mixture a more uniform consistency.

The final compound is a thick, rather stifi liquid but which has sufficient fluidity to be pumped and to be extruded through a nozzle onto the surface to be sealed.

The sealing mastic of the present invention is particularly adaptable for use in bonding and sealing glass or enameled surfaces; For example, in the construction of metal storage vessels or silos from glass coated steel panels, the composition is applied to the edge portions of the adjacent panels in the form of a bead by an extrusion nozzle or any other desired means. The edge portions of the adjacent panels are lapped and mechanically secured together by bolting or the like. The bolting action flattens the beads and the fibrous filler material serves to cushion the bolting and prevents metal-tometal contact between the panels. The sealing composition adheres tightly to the glass panels and provides an air-tight seal at the joint. As the sealing composition will not shrink away from the panels on curing and as it is resistant to the corrosive effect of silage juices and the like, the composition will maintain its sealing eifect for an indefinite period.

The present sealing compound combines the properties of excellent adhesion, excellent internal cohesion and non-shrinkage which were heretofore unobtainable in combination in a sealing compound or mastic. Previously any one of these properties could be obtained only at the expense of the other, so that if a mastic had good adhesion it would either lack cohesion or would shrink excessively. Similarly if it had good cohesion or nonshrinkage it would lack one of the other properties.

To illustrate these properties of adhesion, cohesion and non-shrinkage a glass tube having a length of two inches and an internal diameter of 5 mm. was filled with the present sealing mastic. After standing for a considerable time to insure complete curing, it was noted that the sealing mastic maintained complete contact with the entire internal surface of the tube showing excellent adhesive qualities. There were no internal cracks or openings in the mastic indicating the fine cohesive prop- There was no visible shrinkage of the mastic at any position where it was in contact with the tube and the only shrinkage that occurred was a slight longitudinal shrinkage at the open ends of the tube. This indicates that the sealing mastic will not pull away or shrink from the surface to which it is applied, but the shrinkage, if any, will occur at the portion of the sealing mastic exposed to the atmosphere and shrinkage at this location will not elfect the sealing engagement between the mastic and the surface.

The tubes filled with the cured sealing mastic of the present invention did not fail or leak at a pressure of 30 inches of mercury. That is, with this pressure head of mercury applied to one of the open ends of the tube,

the sealer was not blown out of the tube nor did anyseparations or cracks occur therein to permit leakage of air through the tube. This again illustrates the exceptional adhesive and cohesive properties of the sealing compound.

The present sealing mastic not only adheres well to smooth dry surfaces but also will adhere equally well to wet or moist surfaces. brought about by the combination of the fatty-acid soap and the ammonium salt, makes the mastic particularly adaptable for .use in sealing wet glass coated or wet This property, believed to be enameled surfaces which heretofore have not been suc cessfully sealed due to the lack of adherence between the sealer and the smooth wet surfaces.

The sealing mastic of the invention has an extremely low tack-free time. That is, after the composition is applied to a surface, a cured non-tacky skin will form over the outer surface of the compound in a period of ten minutes or less at room temperatures.

There will be no evidence of cold flow of the sealing compound at ordinary temperatures. over long periods of time the compound will retain its position in a sealed joint and will not tend to move or flow.

This application is a continuation-in-part of the copending application Serial No. 339,185, filed February 26, 1953, of the same inventor, now abandoned.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. A non-aqueous composition for sealing joints between glass coated articles comprising asphalt and ammonium salt and a metal higher fatty-acid soap in an amount by weight of 2% to 6% of said salt and 1% to 3% of said soap.

2. A non-aqueous composition for sealing joints between glass coated articles characterized by being capable of forming an outer tack-free skin in a short period of time and having excellent adhesion to Wet and dry glass surface, comprising 40% to 60% asphalt and 2% to 6% by weight of an ammonium salt and 1% to 3% by weight of a metal higher fatty-acid soap.

3. A composition as claimed in claim 2 wherein said salt and soap are present in a weight ratio of about two parts of salt for each part of soap.

4. A mastic composition comprising the following in- This means that gredients in the proportions given in weight percentages of the total composition:

5. A mastic composition as claimed in claim 4 wherein said salt and soap are present in a weight ratio of two parts of salt to each part of soap.

6. A mastic composition comprising the following ingredients in the proportions given in weight percentages of the total composition:

. Percent Blown-type asphalt to Asphalt solvent 11 to 23 Filler material 20 to 40 2O Ammonium salt 2 to 6 Metal higher fatty-acid soap 1 to 3 Non-drying oil 2 to 6 Anti-oxidant 0.1 to 1 7. A composition as claimed in claim 6 wherein said 5 asphalt has a melting point of about F, and a needle penetration of about 17/ 10mm. at 77 F, said solvent is Xylene, said salt is ammonium chloride, said soap is aluminum stearate and said oil is polybutene.

30 References Cited in the file of this patent UNITED STATES PATENTS 958,210 Allsworth May 17, 1910 2,110,892 Sadtler Mar. 15, 1938 2,382,337 Schiller Aug. 14, 1945 o 2,416,134 Allen Feb. 18, 1947 2,442,706 Olson et al. June 1, 1948 

1. A NON-AQUEOUS COMPOSITION FOR SEALING JOINTS BETWEEN GLASS COATED ARTICLES COMPRISING ASPHALT AND AMMONIUM SALT AND A METAL HIGHER FATTY-ACID SOAP IN AN AMOUNT BY WEIGHT OF 2% TO 6% OF SAID SALT AND 1% TO 3% OF SAID SOAP. 